Marine Weather and Tide Forecast for Mineral, VA

KEY MESSAGES
- 1) Moderating temperatures through midweek.

- 2) Still a chance for wintry precipitation during the mid to late week period associated with multiple shortwaves.

DISCUSSION
KEY MESSAGE 1...Moderating temperatures through midweek.

Winds will gradually subside through Monday as high pressure builds overhead. Despite the lighter winds, enough of a wind is expected to persist tonight in the metro areas to result in wind chills around or a bit below 0F. In the far northwestern suburbs and higher hills of north-central MD (Catoctins, Parr's Ridge, South Mountain), wind chills could approach -10F on the more exposed northwestern facing ridges. To the west, a steady wind this evening into the overnight will pair with air temperatures dropping to near 0F to result in wind chills around -10F. Later during the overnight, high elevation valleys (The Glades in western MD, Canaan Valley in WV) likely radiate very well given high pressure overhead, clear skies, calm winds, very dry air (0.09 inch precipitable water on the 00Z IAD sounding), and a deep snow/ice pack; this should result in localized "bowls" well below 0F (perhaps well into the negative teens).

Heights, thicknesses, and 850 hPa temps all begin a steady rise on Monday, marking a relative warming trend. Despite the strong warm air advection ahead of an approaching warm front late Monday into Tuesday, a lack of deeper moisture should preclude much in the way of precipitation east of the Appalachians. Some precipitation is possible over the mountains, mainly west of the Eastern Continental Divide, due to favorable upslope enhancement both with the warm front early Tuesday, and a subsequent cold front Tuesday night. NBM may be underplaying the magnitude of upslope activity, but it should be light nevertheless with mainly rain transitioning to a light rain/snow mix before ending as wet snow by mid week.

Otherwise, the main story for the region will be milder weather ahead. There is some uncertainty as to just how mild the temperatures get, especially further northeast where they will have the least amount of residence time in the "warm sector" of Tuesday's system. The current forecast calls for most of the region to reach freezing in the lower elevations, with near 40F likely from the South Branch Potomac River Valley, to and across the Shenandoah Valley and the central VA Piedmont on Monday; northeast MD and the higher elevations likely stay in the upper 20s to around 30F. On Tuesday, the current forecast package calls for highs in the upper 30s over northeastern MD, with 40s and 50s most elsewhere (and perhaps near 60F from the South Branch Potomac River Valley into the north-central Shenandoah Valley of VA).

KEY MESSAGE 2...Still a chance for wintry precipitation during the mid to late week period associated with multiple shortwaves.

An upper trough over the northeastern U.S. will begin to make its way eastward starting on Wednesday, and this resulting pressure gradient will cause winds to pick back up to 10-20 knots NW here in the Mid-Atlantic during the later half of the week. Associated with this is a small chance for precipitation, primarily over the Alleghenies. A second shortwave trough coming from the southwest could bring additional impacts to the region towards the end of the week, and this potential second shortwave brings more widespread chances for a wintry mix throughout the CWA starting next Friday and into next weekend.
Model guidance is still fluctuating quite a bit on the dynamics associated with these shortwave troughs, so the timing and magnitude of these events could still change with updated guidance on the evolving upper dynamics behind these features.
Generally speaking, guidance broadly shows a Miller B type low setup chasing a retreating cold airmass that briefly slides over the area late week. This overall signal is quite evident in the 12Z ensemble guidance with a myriad of lows tracking off the southeastern Virginia coast late Sunday/early Monday (Feb 15-16). Details will continue to change so will continue to monitor the situation.

AVIATION /01Z MONDAY THROUGH FRIDAY/
VFR conditions are forecast early this week. An approaching warm front Tuesday could bring some lower CIGs near the mountains, and perhaps some LLWS Tuesday. Otherwise, light NW winds overnight become SE Monday, S to SW Tuesday, then NW Tuesday night. A few gusts near 15 knots are possible Tuesday into Tuesday night.

Winds will begin to pick back up again on Wednesday, corresponding to an upper trough centered over the Northeast before moving offshore by Friday. During this time, NW winds gusting up to 20 knots are possible. Lower CIGs are possible during this timeframe if the trough tracks more southward, but VSBYs should still be predominantly VFR at terminals.

MARINE
Northwest winds will gradually decrease tonight into Monday before flipping around to the southeast. Winds will then pivot to south then southwest as a warm front crosses Tuesday. Milder air over cold (or frozen) water will inhibit mixing and limit wind gusts until a cold front passes Tuesday night turning winds back to the northwest.

For the low water levels, most tidal sites have shown anomalies rebounding and exceeding many of the current forecasts. Will go ahead and let the Low Water Advisories expire on time.

Winds associated with an upper trough later next week will bring 10- 20 knot winds NW between Wednesday and Thursday, and could persist through Friday. SCAs are likely on Thursday, especially in the southern Chesapeake Bay area.

LWX WATCHES/WARNINGS/ADVISORIES
DC...Cold Weather Advisory until 10 AM EST Monday for DCZ001.
MD...Low Water Advisory until midnight EST tonight for MDZ008.
Small Craft Advisory until 10 PM EST this evening for MDZ008.
Cold Weather Advisory until 10 AM EST Monday for MDZ004>006- 008-011-013-014-016-018-501>510.
VA...Cold Weather Advisory until 10 AM EST Monday for VAZ053-054- 501-502-505-506-526-527.
WV...Cold Weather Advisory until 10 AM EST Monday for WVZ501-503- 504.
MARINE...Low Water Advisory until midnight EST tonight for ANZ530.
Small Craft Advisory until 10 PM EST this evening for ANZ530>532-539-540-542.
Cold Weather Advisory until 10 AM EST Monday for ANZ530.
Low Water Advisory until 9 PM EST this evening for ANZ531-535- 538-539.
Small Craft Advisory until 4 AM EST Monday for ANZ533-534-537- 541-543.